This invention relates to a brake apparatus mounted on a hydraulic motor so as to apply a brake force on the motor shaft.
The brake apparatus of the kind specified has been adapted to apply the hydraulic pressure introduced from the high pressure side of a conduit connected to the hydraulic motor on a brake piston thereby to release the shaft brake against the biasing force of a spring. When applying the brake, a control valve for controlling the hydraulic motor is shifted to the neutral position and the hydraulic fluid in a brake chamber is drained when a counterbalancing valve is returned to its neutral position thereby enabling a brake effect to be exerted by the force of the spring.
Such a construction has been disadvantageous in that it requires the provision of a shuttle valve between the counterbalancing valve and the brake apparatus adapted to supply fluid under a high pressure into the brake chamber when the brake is released and drain the high pressure fluid within the brake chamber when the brake is actuated. When using such a shuttle valve, the counterbalancing valve is required to be connected with a drain circuit for draining the brake chamber thereby increasing the manufacturing cost thereof.